2×2 integrated fiber array optical switch and method of operation

ABSTRACT

An optical switch includes an input member, a reflective output member coupled to the input member, and a transmissive output member. The input member supports a plurality of input waveguides, each input waveguide having a reflective surface and operable to receive a corresponding optical signal. The reflective output member supports a plurality of first output waveguides, each first output waveguide coupled to a corresponding input waveguide. The transmissive output member supports a plurality of second output waveguides and has a first position spaced apart from the input member such that the reflective surface of each input waveguide totally internally reflects a corresponding optical signal to a corresponding one of the first output waveguides, and a second position in proximal contact with the input member such that each second output waveguide frustrates the total internal reflection of a corresponding input waveguide and receives a corresponding optical signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to and filed concurrently with pending U.S.patent application Ser. No. 09/713,874, entitled “Integrated Fiber ArrayOptical Switch and Method of Operation,” now U.S. Pat. No. 6,393,175 B1,pending U.S. patent application Ser. No. 09/713,873, entitled “CascadedIntegrated Fiber Array Optical Switch and Method of Operation,” andpending U.S. patent application Ser. No. 09/713,924, entitled“Integrated Fiber Array Optical Switch Using Double-Pass Propagation andMethod of Operation,” now U.S. Pat. No. 6,393,174B1. These applicationshave been commonly assigned to Optical Switch Corporation.

TECHNICAL FIELD OF THE INVENTION

This invention relates to the field of total internal reflection devicesand more particularly to a 2×2 integrated fiber array optical switch.

BACKGROUND OF THE INVENTION

Fiber-optic communication systems include optical components, such asoptical fibers coupled to switching components, that receive, transmit,and otherwise process information in optical signals. The switchingcomponents in a fiber-optic communication system selectively direct theinformation carried by the optical signal to one or more other opticalcomponents. A problem with existing fiber-optic communication systems isthat they require many complex optical components to perform theswitching function. This adds to the cost and size of the fiber-opticcommunication system. It also leads to slower switching speeds anddifficulties with aligning the switching components.

SUMMARY OF THE INVENTION

An integrated fiber array optical switch is provided that substantiallyeliminates or reduces disadvantages and problems associated withprevious optical switches.

In accordance with one embodiment of the present invention, an opticalswitch includes an input member, a reflective output member coupled tothe input member, and a transmissive output member. The input membersupports a plurality of input waveguides, each input waveguide having areflective surface and operable to receive a corresponding opticalsignal. The reflective output member supports a plurality of firstoutput waveguides, each first output waveguide coupled to acorresponding input waveguide. The transmissive output member supports aplurality of second output waveguides and has a first position spacedapart from the input member such that the reflective surface of eachinput waveguide totally internally reflects a corresponding opticalsignal to a corresponding one of the first output waveguides, and asecond position in proximal contact with the input member such that eachsecond output waveguide frustrates the total internal reflection of acorresponding optical signal and receives a corresponding opticalsignal.

Another embodiment of the present invention is an optical switch thatincludes an input member, a reflective output member coupled to theinput member, and a transmissive output member. The input membersupports a first input waveguide, a second input waveguide, a firstoutput waveguide, and a second output waveguide. The first inputwaveguide has a reflective surface and receives a first optical signaland the second input waveguide has a reflective surface and receives asecond optical signal. The reflective output member supports a firstreturn loop waveguide that couples the first input waveguide to thefirst output waveguide, and a second return loop waveguide that couplesthe second input waveguide to the second output waveguide. Thetransmissive output member supports a third return loop waveguide thatcouples the first input waveguide to the second output waveguide, and afourth return loop waveguide that couples the second input waveguide tothe first output waveguide.

The transmissive output member has a first position spaced apart fromthe input member such that the reflective surface of the first inputwaveguide totally internally reflects the first optical signal to thefirst return loop waveguide for communication to the first outputwaveguide and the reflective surface of the second input waveguidetotally internally reflects the second optical signal to the secondreturn loop waveguide for communication to the second output waveguide.The transmissive output member also has a second position in proximalcontact with the input member such that the third return loop waveguidefrustrates the total internal reflection of the first input waveguideand receives the first optical signal for communication to the secondoutput waveguide and the fourth return loop waveguide frustrates thetotal internal reflection of the second input waveguide and receives thesecond optical signal for communication to the first input waveguide.

Yet another embodiment of the present invention is an optical switchthat includes a first input member, a first reflective output membercoupled to the first input member, a first transmissive output, a secondinput member, a second reflective output member coupled to the secondinput member, and a second transmissive output.

The first input member supports a first input waveguide having areflective surface and operable to receive an optical signal. The firstreflective output supports a first intermediate waveguide coupled to thefirst input waveguide. The first transmissive output member supports asecond intermediate waveguide and has a first position spaced apart fromthe input member such that the reflective surface of the input waveguidetotally internally reflects the optical signal to the first intermediatewaveguide, and a second position in proximal contact with the inputmember such that the second intermediate waveguide frustrates the totalinternal reflection of the input waveguide and receives the opticalsignal.

The second input member supports the first intermediate waveguide havinga reflective surface and the second intermediate waveguide having areflective surface. The second reflective output member supports a firstoutput waveguide coupled to the first intermediate waveguide and asecond output waveguide coupled to the second intermediate waveguide.The second transmissive output member supports a third output waveguideand a fourth output waveguide, and has a first position spaced apartfrom the second input member and a second position in proximal contactwith the second input member.

Another embodiment of the present invention is an optical switch thatincludes an input member, a reflective output member coupled to theinput member, and a transmissive output member. The input membersupports an input waveguide having a reflective surface and operable toreceive an optical signal. The reflective output member supports a firstoutput waveguide and a return loop waveguide that is coupled to theinput waveguide and the first output waveguide. The transmissive outputmember supports a second output waveguide and has a first positionspaced apart from the input member such that the reflective surface ofthe input waveguide totally internally reflects the optical signaltoward the return loop waveguide for communication to the first outputwaveguide. The transmissive output member further has a second positionin proximal contact with the input waveguide such that the second outputwaveguide frustrates the total internal reflection of the optical signaland receives the optical signal.

Technical advantages of the present invention include an optical switchthat switches one or more optical signals using waveguides. By usingwaveguides to guide an optical signal to the switching region and toperform the switching operation, the present invention eliminates theneed for costly and sometimes complex optical components. This resultsin a smaller packing density for the optical switch of the presentinvention and a more efficient, faster switching operation.

Another technical advantage provided by the present invention is thatthe optical switches described herein support an array of input andoutput waveguides to facilitate the simultaneous switching of multiplechannels of an optical switch using a common actuator. Yet anothertechnical advantage provided by the present invention is that bycascading a number of optical switches in a particular arrangement, andby selectively operating each individual optical switch, an N×M opticalswitch may be constructed.

While in a switched state, the contact surface of a waveguide istypically placed in proximal contact with a reflective surface ofanother waveguide to frustrate the total internal reflection of theoptical signal. A small portion of the optical signal may be reflected,however, at the reflective surface and processed as though the switch isoperating in the unswitched state. This undesired result is one sourceof a cross-talk signal in the system.

Another technical advantage provided by the present invention is thatthe optical switches described herein reduce the effects of a cross-talksignal generated by the above-identified reflection. In particular, theoptical switches of the present invention process any cross-talk signalsso that a large portion of a cross-talk signal is not received by anoptical component of the optical switch. The negative effects of across-talk signal are thereby reduced.

For example, in the switched state, an undesired cross-talk signalresulting from a residual reflection at the FTIR interface between areflective surface and a contact surface is further processed by areturn-loop waveguide to reduce the crosstalk signal intensity. Inparticular, the crosstalk signal radiation is conveyed by thereturn-loop waveguide to a second FTIR interface within the outputwaveguide signal path. In the switched state this second FTIR waveguideinterface frustrates the total internal reflection of the crosstalksignal at the reflective surface of the output waveguide. As a result,the small, undesired residual portion of the original optical signalundergoes further reduction in its intensity at this second FTIRinterface. Therefore, only a negligible portion of the original opticalsignal, if any, comprises a crosstalk signal that may actually reach anoptical component of the switch. Thus, the crosstalk signal isdissipated and its effects become negligible. This technique is referredto as double-pass propagation. The reduction in the magnitude of thecrosstalk signal in the present invention will be referred to as acrosstalk improvement.

Other technical advantages are readily apparent to one skilled in theart from the following figures, descriptions, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying figures in which like referencenumbers indicate like features and wherein:

FIG. 1 illustrates a 1×2 embodiment of an optical switch in accordancewith the present invention;

FIG. 2A illustrates the 1×2 optical switch operating in an unswitchedmode;

FIG. 2B illustrates the 1×2 optical switch operating in a switched mode;

FIG. 3 illustrates a 1×8 embodiment of an optical switch in accordancewith the present invention;

FIG. 4 illustrates one embodiment of a switching table that details theoperation of the 1×8 optical switch;

FIG. 5 illustrates a 2×2 embodiment of an optical switch in accordancewith the present invention;

FIG. 6A illustrates the 2×2 optical switch operating in an unswitchedmode;

FIG. 6B illustrates the 2×2 optical switch operating in a switched mode;

FIG. 7 illustrates another 2×2 embodiment of an optical switch inaccordance with the present invention;

FIG. 8A illustrates the 2×2 optical switch operating in an unswitchedmode;

FIG. 8B illustrates the 2×2 optical switch operating in a switched mode;

FIG. 9 illustrates yet another 2×2 embodiment of an optical switch inaccordance with the present invention;

FIG. 10A illustrates the 2×2 optical switch operating in an unswitchedmode;

FIG. 10B illustrates the 2×2 optical switch operating in a switchedmode;

FIG. 11 illustrates a 1×2 embodiment of an optical switch using areturned loop waveguide;

FIG. 12A illustrates the 1×2 optical switch using a return loopwaveguide operating in an unswitched mode;

FIG. 12B illustrates the 1×2 optical switch using a return loopwaveguide operating in switched mode;

FIG. 13 illustrates a 2×2 embodiment of an optical switch using a returnloop waveguide;

FIG. 14A illustrates the 2×2 optical switch using a return loopwaveguide operating in an unswitched mode;

FIG. 14B illustrates the 2×2 optical switch using a return loopwaveguide operating in a switched mode; and

FIG. 15 illustrates a 1×8 embodiment of an optical switch using returnloop waveguides.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates one embodiment of an optical switch 10 that includesan input member 12 coupled to a baseplate 14, a reflective output member16 coupled to input member 12, and a transmissive output member 18.Input member 12 supports a plurality of input waveguides 20 and eachwaveguide 20 may receive and transmit a corresponding optical signal 30.Reflective output member 16 supports a plurality of first outputwaveguides 22. Each output waveguide 22 is coupled at one end to one endof a corresponding input waveguide 20. Transmissive output member 18supports a plurality of second output waveguides 24. In general, eachinput waveguide 20 of optical switch 10 receives an optical signal 30and selectively communicates the corresponding signal 30 to acorresponding output waveguide 22 and/or output waveguide 24 based uponthe position of transmissive output member 18. In this respect, FIG. 1illustrates a multi-channel 1×2 optical switch 10.

Input member 12, reflective output member 16, and transmissive outputmember 18 each comprise a structure made of an appropriate material,such as, for example, silicon, that supports each respective waveguide20, 22, and 24. Members 12, 16, and 18 may be formed having grooves 26extending from a first face to a second face of the member 12, 16, and18. Grooves 26 may comprise V-grooves formed on the surface of a member12, 16, or 18, or a channel formed within a member 12, 16, or 18.Waveguides 20, 22, and 24 may be positioned in members 12, 16, and 18,respectively, along a corresponding groove 26. In this respect, grooves26 are used for the precise placement, support, and coupling of theappropriate waveguides 20, 22, and 24. One advantage of members 12, 16,and 18 is that the silicon material can be patterned and implanted toprovide a functional electrical circuit for electronic actuation for usein optical switch 10. Another advantage of members 12, 16, and 18 isthat they support an array of waveguides 20, 22, and 24 to facilitatethe simultaneous switching of multiple channels using a common actuator.

Waveguides 20, 22, and 24 each comprise an optical waveguide formed byany arrangement of suitable optically transmissive material thatcommunicates optical signal 30 as a guided wave of energy. In oneembodiment of switch 10, waveguides 20, 22 and 24 each comprise opticalfibers (referred to generally as input optical fibers 20, and outputoptical fibers 22 and 24). Optical signals 30 comprise visible light,infrared radiation, ultraviolet radiation, or any other suitable opticalbeam propagating at any suitable wavelength.

In another embodiment of switch 10, waveguides 20, 22, and 24 eachcomprise a planar waveguide formed in an appropriate refractivematerial, such as, for example, silicon dioxide, having a particularindex of refraction at a particular wavelength of optical signal 30. Thematerials used to form waveguides 20-24 in the surrounding refractivematerials may be selected to provide particular indices of refractionthat are higher than that of the surrounding refractive materials suchthat waveguides 20-24 communicate signal 30 as a guided wave of energy.In this respect, each of waveguides 20-24 is operable to guide the flowof radiant energy along a path parallel to its axis and to contain theenergy of signal 30 within or adjacent to its surface.

In yet another embodiment of switch 10, a portion of waveguides 20, 22,and 24 comprise optical fibers while the remaining waveguides 20, 22,and 24 comprise planar waveguides to form a hybrid optical fiber/planarwaveguide switch 10. For example, waveguides 20 may comprise planarwaveguides while waveguides 22 and 24 comprise optical fibers. Inanother example, a portion of waveguides 20 and corresponding waveguides22 and 24 comprise planar waveguides, while the remaining portion ofwaveguides 20 and corresponding waveguides 22 and 24 comprise opticalfibers.

Ribbon array 28 comprises a strip or band made from resin, cloth,plastic, or any other suitable material. In general, any suitable numberand combination of waveguides 20, 22, and 24 are bundled in a ribbonarray 28 to position, align, or otherwise support waveguides 20, 22, and24 with relation to members 12, 16, and 18.

Actuator 34 generally comprises a piezoelectric device, a bimorphtransducer, an electromagnetic device, or any other suitable actuationdevice coupled to transmissive output member 18 that displaces member 18in response to an electrical, thermal, or otherwise appropriate controlsignal 36. Activating and deactivating actuator 34 coupled totransmissive output member 18 places member 18 in a selected one of thefirst or second positions such that waveguides 24 are brought out of orinto proximal contact with waveguides 20.

Aligning rails 38 comprise any suitable structure that aligns members12, 16, and 18 with respect to eachother. In one embodiment, aligningrails 38 comprise any suitable structure, such as, for example, opticalfibers or ridges, placed in a channel formed by corresponding V-grooveson the appropriate surfaces of baseplate 14, input member 12, andtransmissive output member 18. For example, V-grooves may be formed on asurface of baseplate 14. Corresponding V-grooves may be formed oncorresponding surfaces of input member 12 and transmissive output member18, to form a channel in which the fiber is placed to align members 12,16, and 18.

In another example, grooves may be formed on a surface of input member12 and a surface of transmissive output member 18. A ridge may be formedon the corresponding surface of baseplate 14 to form aligning rails 18.Of course, grooves may also be formed on a surface of baseplate 14 withgrooves formed on the corresponding surfaces of members 12 and 18.

In another embodiment, aligning rails 28 comprise a combination of holesand pins correspondingly formed in input member 12 and output member 18to control alignment. For example, member 12 may be formed having holesthat extend inward from a first face. Member 18 may be formed havingpins that extend outward from a first face and that mate with the holesformed in member 12. By appropriately mating the pins of member 18 withthe holes of member 12, members 12 and 18 may be aligned. Of course, theholes may also be associated with member 18 and the pins associated withmember 12 to accomplish the same alignment.

In general, aligning rails 38 may be positioned in both the x-axis andy-axis directions to align and/or fix members 12 and 18 with respect toeach other and baseplate 14. For example, aligning rails 38 may be usedas “tracks” to align transmissive output member 18 with input member 12as member 18 is actuated between first and second positions on baseplate14. In another example, aligning rails 38 may be used to fix inputmember 12 in a particular x-y position with respect to baseplate 14.

In yet another example, aligning rails 38 may be used to control therange of movement of output member 18. This is accomplished by forming agroove on the surface of member 18 in a direction orthogonal to thedirection of movement of member 18. A fiber is then placed in thechannel formed by the corresponding grooves of member 18 and baseplate14. The groove of member 18 has a width that is generally greater thanthe width of the groove formed on the surface of baseplate 14. In oneembodiment, the groove of member 18 is formed wide enough to allowmember 18 to travel a predetermined distance before the fiber stops themovement of member 18 at either the first position spaced apart frommember 12 or the second position in proximal contact with member 12. Theextra width of the groove formed on the surface of member 18 facilitatesprecision control of the movement of member 18 with respect to inputmember 12.

In another embodiment, member 18 is formed with the extra wide groove asdiscussed above. However, baseplate 14 is formed with a ridge that, incombination with the groove of member 18, controls the movement ofmember 18 with respect to input member 12. It should be understood thatbaseplate 14 may be formed with a wider groove than that of member 18and/or member 18 may be formed with a ridge, to accomplish the sameresults described above without departing from the scope of the presentinvention.

In operation, optical switch 10 communicates each optical signal 30 froman input fiber 20 to a corresponding output optical fiber 22 whentransmissive output member 18 is spaced apart from input member 12, asdescribed in greater detail with reference to FIG. 2A. When transmissiveoutput member 18 is placed in proximate contact with input member 12,optical switch 10 communicates each optical signal 30 from an inputfiber 20 to a corresponding output optical fiber 24, as described ingreater detail with reference to FIG. 2B.

FIGS. 2A and 2B illustrate in more detail the arrangement of an inputoptical fiber 20 and the corresponding output optical fibers 22 and 24of switch 10. Although FIGS. 2A and 2B illustrate an arrangement of asingle channel of fibers 20, 22, and 24, switch 10 supports multiplechannels of fibers 20, 22, and 24. Each of fibers 20, 22, and 24includes a core 40 designed to transmit or receive information in theform of light pulses, and a cladding 42 that surrounds core 40 toprevent signal 30 from escaping core 40 during transmission. Each core40 of optical fibers 20-24 comprises any suitable refractive material,such as glass, having a particular index of refraction. Each cladding 42of optical fibers 20-24 comprises any suitable refractive material, suchas glass, having an index of refraction lower than that of thecorresponding core 40 such that signal 30 propagates along thelongitudinal axis of an optical fiber 20-24. Optical fibers 20-24 maycomprise a multi-mode fiber having a large core (e.g., 50 or 62.5microns wide) or a single mode fiber having a small core (e.g., 9microns wide). Although the following description is detailed withreference to fibers 20-24 having a circular cross-section, it should beunderstood that the cross-section of fibers 20-24 may have any suitableshape, including, but not limited to, an oval or a circle having groovesor notches.

Input optical fiber 20 comprises reflective surface 43 that forms aninterface between fiber 20 and a refractive material 44. Reflectivesurface 43 of each input optical fiber 20 is at a bias angle withrespect to the longitudinal axis of the input optical fiber 20. Ingeneral, input member 12 comprises a contact face that is at an anglesubstantially similar to the bias angle of a reflective surface 43 of aninput optical fiber 20. This bias angle may be selected to yield anydesired angle of propagation of signal 30 that is totally internallyreflected by reflective surface 43. Therefore, although the bias angleof fiber 20 is illustrated as totally internally reflecting signal 30 ata ninety degree angle in FIG. 2A, the bias angle may be selected tototally internally reflect signal 30 at any suitable angle ofpropagation.

In one embodiment of switch 10, a portion of cladding 42 of fiber 20 iscleaved, etched, lapped, polished, or otherwise removed to form a notch46 so that fiber 22 may be positioned in closer proximity to core 40 offiber 20. Output optical fiber 22 comprises a core 40 that may have anindex of refraction substantially similar to that of core 40 of inputoptical fiber 20. In the embodiment of switch 10 where notch 46 isformed in fiber 20, fiber 22 includes a facet 48 at a bias anglesubstantially similar to the bias angle of reflective surface 43.

Output optical fiber 24 comprises a contact surface 50 at an angle thatis substantially parallel to the bias angle of reflective surface 43. Ingeneral, transmissive output member 18 comprises a contact face that isat an angle substantially similar to the angle of a contact surface 50of an output optical fiber 24. The contact face of transmissive outputmember 18 is in proximal contact with the contact face of input member12 when member 18 is placed in the second position.

The index of refraction of core 40 of fiber 24 is substantially similarto that of core 40 of fiber 20. Member 18 has a first position spacedapart from member 12 and a second position in proximal contact withmember 12. In conjunction with member 18, fiber 24 has a first positionspaced apart from fiber 20 and a second position in proximal contactwith fiber 20 to frustrate the total internal reflection of opticalsignal 30. The term “proximal contact” refers not only to direct contactbetween optical fibers 24 and 20, but also contemplates any spacing orpartial contact between fibers to frustrate the total internalreflection of optical signal 30 to a desired degree. By controllablyvarying the spacing between fibers 24 and 20 to a desired degree,optical switch 10 may perform a beam splitting or variable attenuationoperation such that a desired portion of signal 30 is communicated tofiber 22 and the remaining portion of the signal 30 is communicated tofiber 24. In one embodiment, reflective surface 43 of fiber 20 issubstantially parallel to contact surface 50 of fiber 24 when fiber 24is placed in proximal contact with fiber 20 such that the longitudinalaxis of fiber 20 is substantially aligned with the longitudinal axis offiber 24.

Refractive material 44 comprises air or any other suitable substancethat has an index of refraction lower than that of core 40 of opticalfiber 20. Optical signal 30 contacts reflective surface 43 at an inputangle. If the input angle at which signal 30 contacts reflective surface43 is equal to or above a critical angle of refraction associated withthe interface between core 40 of fiber 20 and refractive material 44,then reflective surface 43 totally internally reflects optical signal 30at an output angle that is generally determined based upon the inputangle of signal 30. Reflective surface 43 of fiber 20 therefore reflectsoptical signal 30 by total internal reflection (TIR).

In operation of optical switch 10 with transmissive output member 18spaced apart from input member 12 and, therefore, output fiber 24 spacedapart from input fiber 20, as illustrated in FIG. 2A, fiber 20communicates optical signal 30 through core 40 as indicated by arrow 52.Total internal reflection at reflective surface 43, the interfacebetween core 40 of fiber 20 and refractive material 44, directs signal30 through cladding 42 of fiber 20 and into core 40 of output opticalfiber 22, as indicated by arrow 54. By placing output optical fiber 22closer to core 40 of input optical fiber 20 using notch 46 of fiber 20and facet 48 of fiber 22, switch 10 reduces the amount of cladding 42through which optical signal 30 propagates from core 40 of fiber 20 tocore 40 of fiber 22. In this respect, switch 10 reduces the divergenceand, therefore, the insertion loss of optical signal 30. Moreover,switch 10 reduces any “lensing” effects.

Transmissive output member 18 is placed in proximal contact with inputmember 12 such that contact surface 50 of fiber 24 is placed in proximalcontact with reflective surface 43 of fiber 20. In operation of switch10 with output optical fiber 24 placed in proximal contact with inputoptical fiber 20, as illustrated in FIG. 2B, fiber 20 communicatesoptical signal 30 through core 40 as indicated by arrow 52. Core 40 offiber 24 having an index of refraction substantially similar to core 40of fiber 20, frustrates the total internal reflection of optical signal30 at reflective surface 43. As a result, core 40 of fiber 24 receivesoptical signal 30 from core 40 of fiber 20. Optical signal 30 propagatesthrough fiber 24 in a direction indicated by arrow 56. Therefore, FIGS.2A and 2B together illustrate the operation of switch 10 with fiber 24spaced apart from fiber 20 and with fiber 24 placed in proximal contactwith fiber 20, respectively.

By using members 12, 16, and 18 to support an array of waveguides 20,22, and 24 during the switching operation, switch 10 facilitates thesimultaneous switching of multiple channels. In this respect, opticalswitch 10 comprises an N-channel 1×2 optical switch.

FIG. 3 illustrates one embodiment of an optical switch 100 that includesoptical switches 10 a, 10 b, and 10 c arranged in a cascadedarchitecture to form a 1×8 optical switch. Optical switch 10 a includesan input member 12, a reflective output member 16, and a transmissiveoutput member 18. Input member 12 of switch 10 a supports an input fiber20. Reflective output member 16 a supports output fiber 22 a.Transmissive output member 18 a supports output fiber 24 a. As switch 10a includes one input channel and two output channels, switch 10 acomprises a 1×2 optical switch.

Input member 12 b of switch 10 b receives output fibers 22 a and 24 a ofswitch 10 a as input fibers for switch 10 b. In this respect, outputfibers 22 a and 24 a comprise intermediate optical fibers for switch100. Reflective output member 16 b supports output fibers 22 b andtransmissive output member 18 b supports output fibers 24 b. As switch10 b includes two input channels and four output channels, switch 10 bcomprises a multi-channel 1×2 optical switch. In this respect, thecombination of switches 10 a and 10 b comprises a 1×4 optical switch.

Input member 12 c receives output fibers 22 b and 24 b as input fibersto switch 10 c. In this respect, output fibers 22 b and 24 b compriseintermediate optical fibers for switch 100. Reflective output member 16c supports four output fibers 22 c and transmissive output member 18 csupports four output fibers 24 c. As switch 10 c includes four inputchannels and eight output channels, switch 10c comprises a multi-channel1×2 optical switch. The combination of switches 10 a, 10 b, and 10 ctherefore comprises a 1×8 optical switch. Although optical switch 100 isillustrated having optical switches 10 a, 10 b, and 10 c arranged toform a 1×8 optical switch, it should be understood that optical switch100 may include any number and combination of optical switches 10appropriately arranged to form a 1×N optical switch.

The operation of switch 100 illustrated in FIG. 3 is described withreference to the switch states illustrated in switching table 150 ofFIG. 4. Referring to FIG. 4, table 150 includes columns 152, 154, and156 that identify the states of switches 10 a, 10 b, and 10 c,respectively. As illustrated in switching table 150, a particular switch10 may be in an “OFF” state or an “ON” state. When a switch 10 is in the“OFF” state, the transmissive output member 18 of the switch 10 is inthe first position spaced apart from the input member 12 of the switch10. When a switch 10 is in the “ON” state, the transmissive outputmember 18 is in the second position in proximal contact with the inputmember 12 of the switch 10. Table 150 further includes column 158 thatidentifies the output channel of an optical signal 30 for any givenoperation of switches 10 a, 10 b, and 10 c, as identified in rows160-174.

Referring to row 160, switches 10 a, 10 b, and 10 c are each in the“OFF” state. In this regard, transmissive output member 18 a is spacedapart from input member 12 a. Input fiber 20 communicates optical signal30. Total internal reflection at reflective surface 43 of input fiber 20directs signal 30 to output fiber 22 a which is the second input channelfor input member 12 b. With switch 10 b in the “OFF” state, transmissiveoutput member 18 b is spaced apart from input member 12 b. Therefore,total internal reflection at reflective surface 43 of fiber 22 a directssignal 30 to the output fiber 22 b that enters the fourth input channelof input member 12 c. With switch 10 c in the “OFF” state, transmissiveoutput member 18 c is spaced apart from input member 12 c. Therefore,total internal reflection at reflective surface 43 of the appropriatefiber 22 b directs signal 30 to the output fiber 22 c that is the eighthoutput channel of switch 10 c.

Referring to row 162, switches 10 a and 10 b are in the “OFF” state and10 c is in the “ON” state. In this regard, transmissive output member 18a is spaced apart from input member 12 a. Input fiber 20 communicatesoptical signal 30. Total internal reflection at reflective surface 43 ofinput fiber 20 directs signal 30 to output fiber 22 a which is thesecond input channel for input member 12 b. With switch 10 b in the“OFF” state, transmissive output member 18 b is spaced apart from inputmember 12 b. Therefore, total internal reflection at reflective surface43 of fiber 22 a directs signal 30 to the output fiber 22 b that entersthe fourth input channel of input member 12 c. With switch 10 c in the“ON” state, transmissive output member 18 c is placed in proximalcontact with input member 12 c. Therefore, an appropriate output fiber24 c frustrates the total internal reflection of optical signal 30 atreflective surface 43 of the fiber 22 b. As a result, the output fiber24 c that is the fourth output channel of switch 10 c receives opticalsignal 30.

Referring to row 164, switches 10 a and 10 c are each in the “OFF” stateand switch 10 b is in the “ON” state. In this regard, transmissiveoutput member 18 a is spaced apart from input member 12 a. Input fiber20 communicates optical signal 30. Total internal reflection atreflective surface 43 of input fiber 20 directs signal 30 to outputfiber 22 a which is the second input channel for input member 12 b. Withswitch 10 b in the “ON” state, transmissive output member 18 b is placedin proximal contact with input member 12 b. Therefore, an appropriateoutput fiber 24 b frustrates the total internal reflection of opticalsignal 30 at reflective surface 43 of fiber 22 a. As a result, fiber 24b receives optical signal 30 and enters the second channel of inputmember 12 c. With switch 10 c in the “OFF” state, transmissive outputmember 18 c is spaced apart from input member 12 c. Therefore, totalinternal reflection at reflective surface 43 of the appropriate fiber 24b directs signal 30 to the output fiber 22 c that is the sixth outputchannel of switch 10 c.

Referring to row 166, switch 10 a is in the “OFF” state and switches 10b and 10 c are each in the “ON” state. In this regard, transmissiveoutput member 18 a is spaced apart from input member 12 a. Input fiber20 communicates optical signal 30. Total internal reflection atreflective surface 43 of input fiber 20 directs signal 30 to outputfiber 22 a which is the second input channel for input member 12 b. Withswitch 10 b in the “ON” state, transmissive output member 18 b is placedin proximal contact with input member 12 b. Therefore, an appropriateoutput fiber 24 b frustrates the total internal reflection of opticalsignal 30 at reflective surface 43 of fiber 22 a. As a result, fiber 24b receives optical signal 30 and enters the second channel of inputmember 12 c. With switch 10 c in the “ON” state, transmissive outputmember 18 c is placed in proximal contact with input member 12 c.Therefore, an appropriate output fiber 24 c frustrates the totalinternal reflection of optical signal 30 at reflective surface 43 of thefiber 24 b. As a result, the output fiber 24 c that is the second outputchannel of switch 10 c receives optical signal 30.

Referring to row 168, switch 10 a is in the “ON” state and switches 10 band 10 c are each in the “OFF” state. In this regard, transmissiveoutput member 18 a is placed in proximal contact with input member 12 a.Fiber 20 communicates optical signal 30. Fiber 24 a frustrates the totalinternal reflection of optical signal 30 at reflective surface 43 offiber 20. As a result, fiber 24 a receives optical signal 30 and entersthe first channel of input member 12 b. With switch 10 b in the “OFF”state, transmissive output member 18 b is spaced apart from input member12 b. Therefore, total internal reflection at reflective surface 43 offiber 24 a directs signal 30 to the output fiber 22 b that enters thethird input channel of input member 12 c. With switch 10 c in the “OFF”state, transmissive output member 18 c is spaced apart from input member12 c. Therefore, total internal reflection at reflective surface 43 ofthe appropriate fiber 22 b directs signal 30 to the output fiber 22 cthat is the seventh output channel of switch 10 c.

Referring to row 170, switches 10 a and 10 c are in the “ON” state andswitch 10 b is in the “OFF” state. In this regard, transmissive outputmember 18 a is placed in proximal contact with input member 12 a. Fiber20 communicates optical signal 30. Fiber 24 a frustrates the totalinternal reflection of optical signal 30 at reflective surface 43 offiber 20. As a result, fiber 24 a receives optical signal 30 and entersthe first channel of input member 12 b. With switch 10 b in the “OFF”state, transmissive output member 18 b is spaced apart from input member12 b. Therefore, total internal reflection at reflective surface 43 offiber 24 a directs signal 30 to the output fiber 22 b that enters thethird input channel of input member 12 c. With switch 10 c in the “ON”state, transmissive output member 18 c is placed in proximal contactwith input member 12 c. Therefore, an appropriate output fiber 24 cfrustrates the total internal reflection of optical signal 30 atreflective surface 43 of the fiber 22 b. As a result, the output fiber24 c that is the third output channel of switch 10 c receives opticalsignal 30.

Referring to row 172, switches 10 a and 10 b are in the “ON” state andswitch 10 c is in the “OFF” state. In this regard, transmissive outputmember 18 a is placed in proximal contact with input member 12 a. Fiber20 communicates optical signal 30. Fiber 24 a frustrates the totalinternal reflection of optical signal 30 at reflective surface 43 offiber 20. As a result, fiber 24 a receives optical signal 30 and entersthe first channel of input member 12 b. With switch 10 b in the “ON”state, transmissive output member 18 b is placed in proximal contactwith input member 12 b. Therefore, an appropriate output fiber 24 bfrustrates the total internal reflection of optical signal 30 atreflective surface 43 of fiber 24 a. As a result, fiber 24 b receivesoptical signal 30 and enters the first channel of input member 12 c.With switch 10 c in the “OFF” state, transmissive output member 18 c isspaced apart from input member 12 c. Therefore, total internalreflection at reflective surface 43 of the appropriate fiber 24 bdirects signal 30 to the output fiber 22 c that is the fifth outputchannel of switch 10 c.

Referring to row 174, switches 10 a, 10 b, and 10 c are a each in the“ON” state. In this regard, transmissive output member 18 a is placed inproximal contact with input member 12 a. Fiber 20 communicates opticalsignal 30. Fiber 24 a frustrates the total internal reflection ofoptical signal 30 at reflective surface 43 of fiber 20. As a result,fiber 24 a receives optical signal 30 and enters the first channel ofinput member 12 b. With switch 10 b in the “ON” state, transmissiveoutput member 18 b is placed in proximal contact with input member 12 b.Therefore, an appropriate output fiber 24 b frustrates the totalinternal reflection of optical signal 30 at reflective surface 43 offiber 24 a. As a result, fiber 24 b receives optical signal 30 andenters the first channel of input member 12 c. With switch 10 c in the“ON” state, transmissive output member 18 c is placed in proximalcontact with input member 12 c. Therefore, an appropriate output fiber24 c frustrates the total internal reflection of optical signal 30 atreflective surface 43 of the fiber 24 b. As a result, the output fiber24 c that is the first output channel of switch 10 c receives opticalsignal 30.

FIG. 5 illustrates one embodiment of a 2×2 optical switch 200 thatincludes input member 12 coupled to baseplate 14, reflective outputmember 16 coupled to input member 12, and transmissive output member 18having a first position spaced apart from input member 12 and a secondposition in proximal contact with input member 12. Input member 12supports input waveguides 202 a and 202 b as well as output waveguides204 a and 204 b. Reflective output member 16 supports a first returnloop waveguide 206 a that couples waveguide 202 a to waveguide 204 a,and a second return loop waveguide 206 b that couples waveguide 202 b towaveguide 204 b. Transmissive output member 18 supports a third returnloop waveguide 206 c that couples waveguide 202 a to waveguide 204 b,and a fourth return loop waveguide 206 d that couples waveguide 202 b towaveguide 204 a.

Waveguides 202 a-b, 204 a-b, and 206 a-d each comprise an opticalwaveguide formed by an arrangement of suitable optically transmissivematerial that communicates optical signal 30 as a guided wave of energy.In one embodiment of switch 200, waveguides 202 a-b, 204 a-b, and 206a-d each comprise optical fibers (referred to generally as fibers 202a-b, 204 a-b, and 206 a-d). In general, fibers 202 a-b, 204 a-b, and 206a-d each include a core 40 and a cladding 42, as described above withregard to fibers 20-24. In addition, fibers 202 a-b and 204 a-b includea reflective surface 43 and fibers 206 a-d include a contact surface 50,as described above with regard to fibers 20-24. In another embodiment ofswitch 200, waveguides 202 a-b, 204 a-b, and 206 a-d each comprise aplanar waveguide formed in an appropriate refractive material, asdescribed above with regard to waveguides 20-24. In yet anotherembodiment, waveguides 202 a-b, 204 a-b, and 206 a-d each comprise anoptical fiber and/or a planar waveguide, as described above with regardto waveguides 20-24, to form a hybrid optical fiber/planar waveguideoptical switch 200.

In operation, each of input fibers 202 a and 202 b communicates acorresponding optical signal 30 to a selected one of output opticalfibers 204 a or 204 b based upon the position of transmissive outputmember 18. For example, optical switch 200 communicates optical signal30 a from input optical fiber 202 a to output optical fiber 204 a, andinput optical signal 30 b from input optical fiber 202 b to outputoptical fiber 204 b, when transmissive output member 18 is spaced apartfrom input member 12, as described in greater detail with reference toFIG. 6A. Optical switch 200 communicates optical signal 30 a from inputoptical fiber 202 a to output optical fiber 204 b, and optical signal 30b from input optical fiber 202 b to output optical fiber 204 a whentransmissive output member 18 is placed in proximal contact with inputmember 12, as described in greater detail with reference to FIG. 6B.

In operation of optical switch 200 with return loop fibers 206 c and 206d spaced apart from input optical fibers 202 a and 202 b, as illustratedin FIG. 6A, fibers 202 a and 202 b communicate optical signals 30 a and30 b, respectively. Total internal reflection at reflective surface 43of input fiber 202 a directs optical signal 30 a to output optical fiber204 a via return loop fiber 206 a. Total internal reflection atreflective surface 43 of input optical fiber 202 b directs opticalsignal 30 b to output optical fiber 204 b via return loop fiber 206 b.

In operation of optical switch 200 with return loop fibers 206 c and 206d in proximal contact with input fibers 202 a and 202 b, as illustratedin FIG. 6B, fibers 202 a and 202 b communicate optical signals 30 a and30 b, respectively. Return loop fiber 206 c frustrates the totalinternal reflection of optical signal 30 a at reflective surface 43 ofinput optical fiber 202 a. As a result, return loop fiber 206 c receivesoptical signal 30 a and communicates signal 30 a to output optical fiber204 b. Return loop fiber 206 d frustrates the total internal reflectionof optical signal 30 b at reflective surface 43 of input fiber 202 b. Asa result, return loop fiber 206 d receives optical signal 30 b andcommunicates signal 30 b to output optical fiber 204 a. Therefore, FIGS.6A and 6B together illustrate the operation of switch 200 with fibers206 c and 206 d spaced apart from fibers 202 a and 202 b, respectively,and with fibers 206 c and 206 d placed in proximal contact with fibers202 a and 202 b, respectively.

FIG. 7 illustrates one embodiment of a 2×2 optical switch 300 thatincludes first input member 12 a coupled to baseplate 14 a, firstreflective output member 16 a coupled to input member 12 a, and firsttransmissive output member 18 a having a first position spaced apartfrom input member 12 a and a second position in proximal contact withinput member 12 a. First input member 12 a supports input waveguides 302a and 302 b. First reflective output member 16 a supports a firstintermediate waveguide 306 a, and a second intermediate waveguide 306 b,also referred to as return-loop waveguides 306 a and 306 b. Transmissiveoutput member 18 a supports a third intermediate waveguide 306 c, and afourth intermediate waveguide 306 d, also referred to as return-loopwaveguides 306 c and 306 d.

Optical switch 300 further includes a second input member 12 b coupledto a baseplate 14 b, a second reflective output member 16 b coupled toinput member 12 b, and a second transmissive output member 18 b having afirst position spaced apart from input member 12 and a second positionplaced in proximal contact with input member 12 b. Input member 12 bsupports output waveguides 304 a and 304 b. Reflective output member 16b supports intermediate waveguides 306 c and 306 d received fromtransmissive output member 18 a. Transmissive output member 18 bsupports intermediate waveguides 306 a and 306 b received fromreflective output member 16 a.

Waveguides 302 a-b, 304 a-b, and 306 a-d each comprise an opticalwaveguide formed by an arrangement of suitable optically transmissivematerial that communicates optical signal 30 as a guided wave of energy.In one embodiment of switch 300, waveguides 302 a-b, 304 a-b, and 306a-d each comprise optical fibers (referred to generally as fibers 302a-b, 304 a-b, and 306 a-d, respectively). In general, fibers 302 a-b,304 a-b, and 306 a-d each include a core 40 and a cladding 42, asdescribed above with regard to fibers 20-24. In addition, fibers 302 a-band 304 a-b include a reflective surface 43 and fibers 306 a-d include acontact surface 50, as described above with regard to fibers 20-24. Inanother embodiment of switch 300, waveguides 302 a-b, 304 a-b, and 306a-d each comprise a planar waveguide formed in an appropriate refractivematerial, as described above with regard to waveguides 20-24. In yetanother embodiment, waveguides 302 a-b, 304 a-b, and 306a-d eachcomprise an optical fiber and/or a planar waveguide, as described abovewith regard to waveguides 20-24, to form a hybrid optical fiber/planarwaveguide optical switch 300.

In operation, each of input fibers 302 a and 302 b communicates acorresponding optical signal 30 to a selected one of output opticalfibers 304 a or 304 b based upon the position of transmissive outputmembers 18 a and 18 b. For example, optical switch 300 communicatesoptical signal 30 a from input optical fiber 302 a to output opticalfiber 304 a, and input optical signal 30 b from input optical fiber 302b to output optical fiber 304 b, when transmissive output member 18 a isspaced apart from input member 12 a and transmissive output member 18 bis placed in proximal contact with input member 12 b, as described ingreater detail with reference to FIG. 8A. Optical switch 300communicates optical signal 30 a from input optical fiber 302 a tooutput fiber 304 b, and optical signal 30 b from input optical fiber 302b to output fiber 304 a when transmissive output member 18 a is placedin proximal contact with input member 12 a and transmissive outputmember 18 b is spaced apart from input member 12 b, as described ingreater detail with reference to FIG. 8B.

In operation of optical switch 300 with intermediate fibers 306 c and306 d spaced apart from input optical fibers 302 a and 302 b, andintermediate fibers 306 a and 306 b placed in proximal contact withoutput fibers 304 a and 304 b, respectively, as illustrated in FIG. 8A,fibers 302 a and 302 b communicate optical signals 30 a and 30 b,respectively. Total internal reflection at reflective surface 43 ofinput fiber 302 a directs optical signal 30 a to output optical fiber304 a via intermediate fiber 306 a. Total internal reflection atreflective surface 43 of input optical fiber 302 b directs opticalsignal 30 b to output optical fiber 304 b via intermediate fiber 306 b.

In operation of optical switch 300 with intermediate fibers 306 c and306 d in proximal contact with input fibers 302 a and 302 b, andintermediate fibers 306 a and 306 b spaced apart from fibers 304 a and304 b, as illustrated in FIG. 8B, fibers 302 a and 302 b communicateoptical signals 30 a and 30 b, respectively. Intermediate fiber 306 cfrustrates the total internal reflection of optical signal 30 a atreflective surface 43 of input optical fiber 302 a. As a result,intermediate fiber 306 c receives optical signal 30 a and communicatessignal 30 a to output optical fiber 304 b due to total internalreflection at reflective surface 43 of fiber 304 b. Intermediate fiber306 d frustrates the total internal reflection of optical signal 30 b atreflective surface 43 of input fiber 302 b. As a result, intermediatefiber 306 d receives optical signal 30 b and communicates signal 30 b tooutput optical fiber 304 a due to total internal reflection atreflective surface 43 of fiber 304 a. Therefore, FIGS. 8A and 8Btogether illustrate the operation of switch 300.

FIG. 9 illustrates one embodiment of a 2×2 optical switch 400 thatincludes first input member 12 a coupled to first reflective outputmember 16 a, and second input member 12 b coupled to second reflectiveoutput member 16 b. Second reflective output member 16 b has a firstposition spaced apart from first input member 12 a and a second positionin proximal contact with first input member 12 a. First input member 12a supports input waveguide 402 a. First reflective output member 16 asupports first output waveguide 404 a. Second input member 12 b supportssecond input waveguide 402 b. Second reflective output member 16 bsupports second output waveguide 404 b.

Waveguides 402 a-b and 404 a-b each comprise an optical waveguide formedby an arrangement of suitable optically transmissive material thatcommunicates optical signal 30 as a guided wave of energy. In oneembodiment of switch 400, waveguides 402 a-b and 404 a-b each compriseoptical fibers (referred to generally as fibers 402 a-b and 404 a-b). Ingeneral, fibers 402 a-b and 404 a-b each include a core 40 and acladding 42, as described above with regard to fibers 20-24. Inaddition, fiber 402 a includes a reflective surface 43 and fiber 404 bincludes a contact surface 50, as described above with regard to fibers20-24. In another embodiment of switch 400, waveguides 402 a-b and 404a-b each comprise a planar waveguide formed in an appropriate refractivematerial, as described above with regard to waveguides 20-24. In yetanother embodiment, waveguides 402 a-b and 404 a-b each comprise anoptical fiber and/or a planar waveguide, as described above with regardto waveguides 20-24, to form a hybrid optical fiber/planar waveguideoptical switch 400.

In operation, each of input fibers 402 a and 402 b communicates acorresponding optical signal 30 to a selected one of output opticalfibers 404 a or 404 b based upon the position of second reflectiveoutput member 16 b. For example, optical switch 400 communicates opticalsignal 30 a from input optical fiber 402 a to output optical fiber 404a, and input optical signal 30 b from input optical fiber 402 b tooutput optical fiber 404 b, when second reflective output member 16 b isspaced apart from first input member 12 a, as described in greaterdetail with reference to FIG. 10A. Optical switch 400 communicatesoptical signal 30 a from input optical fiber 402 a to output opticalfiber 404 b, and optical signal 30 b from input optical fiber 402 b tooutput optical fiber 404 a when second reflective output member 16 b isplaced in proximal contact with first input member 12 a, as described ingreater detail with reference to FIG. 10B.

In operation of optical switch 400 with output fiber 404 b spaced apartfrom input fiber 402 a, as illustrated in FIG. 10A, fibers 402 a and 402b communicate optical signals 30 a and 30 b, respectively. Totalinternal reflection at reflective surface 43 of input fiber 402 adirects optical signal 30 a to output fiber 404 a. Total internalreflection at contact surface 50 of output fiber 404 b directs opticalsignal 30 b to fiber 404 b.

In operation of optical switch 400 with fiber 404 b placed in proximalcontact with fiber 402 a, as illustrated in FIG. 10B, fibers 402 a and402 b communicate optical signals 30 a and 30 b, respectively. Fiber 404b frustrates the total internal reflection of optical signal 30 a atreflective surface 43 of input fiber 402 a. As a result, output fiber404 b receives optical signal 30 a. Input fiber 402 a frustrates thetotal internal reflection of optical signal 30 b at contact surface 50of output fiber 404 b. As a result, output fiber 404 a receives opticalsignal 30 b. Therefore, FIGS. 10A and 10B together illustrate theoperation of switch 400.

FIG. 11 illustrates one embodiment of a 1×2 optical switch 500 thatincludes input member 12, reflective output member 16 coupled to inputmember 12, and transmissive output member 18 having a first positionspaced apart from input member 12 and a second position in proximalcontact with input member 12. Input member 12 supports input waveguide502. Reflective output member 16 supports first output waveguide 504 aand a return loop waveguide 506. Transmissive output member 18 supportsa second output waveguide 504 b, and a switching waveguide 508.

Waveguides 502, 504 a-b, 506, and 508 each comprise an optical waveguideformed by an arrangement of suitable optically transmissive materialthat communicates optical signal 30 as a guided wave of energy. In oneembodiment of switch 500, waveguides 502, 504 a-b, 506, and 508 eachcomprise optical fibers (referred to generally as fibers 502, 504 a-b,506 and 508, respectively). In general, fibers 502, 504 a-b, 506, and508 each include a core 40 and a cladding 42, as described above withregard to fibers 20-24. In addition, fibers 502 and 506 include areflective surface 43 and fibers 504 b and 508 include a contact surface50, as described above with regard to fibers 20-24. In anotherembodiment, fiber 506 includes a reflective surface 43 that operates inconjunction with contact surface 50 of fiber 504 b, and fiber 504 aincludes a reflective surface 43′ that operates in conjunction withfiber 508. In another embodiment of switch 500, waveguides 502, 504 a-b,506 and 508 each comprise a planar waveguide formed in an appropriaterefractive material, as described above with regard to waveguides 20-24.In yet another embodiment, waveguides 502, 504 a-b, and 506, and 508each comprise an optical fiber and/or a planar waveguide, as describedabove with regard to waveguides 20-24, to form a hybrid opticalfiber/planar waveguide optical switch 500.

In operation, input fiber 502 communicates an optical signal 30 to aselected one of output optical fibers 504 a or 504 b based upon theposition of transmissive output number 18 a. A technical advantageprovided by the present invention is that the optical switch 500 reducesthe effects of cross-talk signals. For example, while transmissiveoutput member 18 is placed in proximal contact with input member 12, thecontact surface 50 of output fiber 504 b is placed in proximal contactwith reflective surface 43 of input fiber 502 to frustrate the totalinternal reflection of optical signal 30. A small portion of opticalsignal 30 may be reflected, however, at reflective surface 43 andprocessed as though optical switch 500 is operating in the unswitchedstate. This undesired result is one source of a cross-talk signal in thesystem. Optical switch 500 uses double-pass propagation to process anysuch cross-talk signals so that a large portion of the cross-talksignals is not received by an optical component, such as output fiber504 a, of optical switch 500. The negative effects of a cross-talksignal are thereby reduced.

FIG. 12A illustrates optical switch 500 with output optical fiber 504 band switching fiber 508 spaced apart from input fiber 502 and outputfiber 504 a, respectively. In operation, input fiber 502 communicatesoptical signal 30. Total internal reflection at reflective surface 43 ofinput fiber 502 directs optical signal 30 to return loop fiber 506.Total internal reflection at reflective surface 43 of return loop fiber506 directs optical signal 30 to output fiber 504 a.

FIG. 12B illustrates optical switch 500 with output fiber 504 b andswitching fiber 508 placed in proximal contract with input fiber 502 andoutput fiber 504 a, respectively. In operation, input fiber 502communicates optical signal 30. Contact surface 50 of output opticalfiber 504 b frustrates the total internal reflection of optical signal30 at reflective surface 43 of input fiber 502. As a result, outputoptical fiber 504 b receives almost all of signal 30. Ideally, contactsurface 50 of fiber 504 b frustrates the total internal refection of theentire signal 30 at reflective surface 43 such that signal 30 iscommunicated into fiber 504 b, as illustrated using a solid line forsignal 30. Reflection of a small, residual portion of signal 30 at theinterface between surfaces 43 and 50 may result in a cross-talk signal510, as illustrated using a dashed line. A technical advantage providedby switch 500 illustrated in FIGS. 11, 12A and 12B is that switch 500minimizes the amount of cross-talk signal 510 that is received by fiber504 a, or any other optical component of switch 500.

Referring to FIG. 12B, return loop optical fiber 506 propagatescross-talk signal 510 toward a reflective surface 43. Switching fiber508 frustrates the total internal reflection of cross-talk signal 510 atreflective surface 43 of return loop fiber 506. This technique may bereferred to as double-pass propagation because cross-talk signal 510 issubjected to a second FTIR interface. Only a negligible residual portionof cross-talk signal 510, if any, is directed by total internalreflection into fiber 504 a. Almost all of cross-talk signal 510 isdirected away from any of the optical components of switch 500.Therefore, switch 500 reduces the effects of cross-talk signal 510 andresults in what is generally referred to as a cross-talk improvement.

FIG. 13 illustrates one embodiment of a 2×2 optical switch 600 thatincludes a first input member 12 a coupled to a first reflective outputmember 16 a, and a second input member 12 b coupled to a secondreflective output member 16 b. Second input member 12 b has a firstposition spaced apart from the first input member 12 a and a secondposition in proximal contact with first input member 12 a. First inputmember 12 a supports first input waveguide 602 a and second outputwaveguide 604 b. Second input member 12 b supports second inputwaveguide 602 b and first output waveguide 604 a. First reflectiveoutput member 16 a supports first return loop waveguide 606 a. Secondreflective output member 16 b supports second return loop waveguide 606b.

Waveguides 602 a-b, 604 a-b and 606 a-b each comprise an opticalwaveguide formed by an arrangement of suitable optically transmissivematerial that communicates optical signal 30 as a guided wave of energy.In one embodiment of switch 600, waveguides 602 a-b, 604 a-b, and 606a-b each comprise optical fibers (referred to generally as fibers 602a-b, 604 a-b, and 606 a-b). In general, fibers 602 a-b, 604 a-b, and 606a-b each includes a core 40 and a cladding 42, as described about withregard to fibers 20-24. In addition, fibers 602 a and 604 b include areflective surface 43 and fibers 602 b and 604 a include a contactsurface 50, as described above with regard to fibers 20-24. In anotherembodiment of switch 600, waveguides 602 a-b, 604 a-b, and 606 a-b eachcomprise a planar waveguide formed in an appropriate refractivematerial, as described above with regard to waveguides 20-24. In yetanother embodiment, waveguides 602 a-b, 604 a-b, and 606 a-b eachcomprise an optical fiber and/or a planar waveguide, as described abovewith regard to waveguides 20-24, to form a hybrid optical fiber/planarwaveguide optical switch 600.

In operation, each of input fibers 602 a and 602 b communicates acorresponding optical signal 30 to a selected one of output opticalfibers 604 a or 604 b based upon the position of second input member 12b. For example, optical switch 600 communicates optical signal 30 a frominput optical fiber 602 a to output optical fiber 604 b, and inputoptical signal 30 b from input optical fiber 602 b to output opticalfiber 602 a, when second input member 12 b is spaced apart from firstinput member 12 a, as described in greater detail with reference to FIG.14A. Optical switch 600 communicates optical signal 30 a from inputoptical fiber 602 a to output optical fiber 602 a, and optical signal 30b from input optical fiber 602 b to output optical fiber 604 b whensecond input member 12 b in placed in proximal contact with first inputmember 12 a, as described in greater detail with reference to FIG. 14B.

In operation of optical switch 600 with output fiber 604 a and inputfiber 602 b in proximal contact with input fiber 602 a and output fiber604 b, respectively, as illustrated in FIG. 14A, fibers 602 a and 602 bcommunicate optical signals 30 a and 30 b, respectively. Total internalreflection at reflective surface 43 of input fiber 602 a directs opticalsignal 30 a to return loop fiber 606 a. Total internal reflection atreflective surface 43 of fiber 604 b directs signal 30 a into outputfiber 604 b. Input fiber 602 b communicates optical signal 30 b. Totalinternal reflection at contact surface 50 of fiber 602 b directs signal30 b to return loop optical fiber 606 b. Return loop fiber 606 bpropagates optical signal 30 b toward contact surface 50 of input fiber604 a. Total internal reflection of signal 30 b at contact surface 50 offiber 604 a directs signal 30 b into fiber 604 a. In this respect, inputfiber 602 communicates optical signal 30 a to output fiber 604 b.Furthermore, input fiber 602 b communicates optical signal 30 b tooutput fiber 604 a.

In operation of switch 600 with fibers 604 a and 602 b in proximalcontact with fibers 602 a and 604 b, respectively, as illustrated inFIG. 14B, fibers 602 a and 602 b communicate optical signal 30 a and 30b, respectively. Contact surface 50 of fiber 604 a frustrates the totalinternal reflection of optical signal 30 a at reflective surface 43 ofinput fiber 602 a. As a result, fiber 604 a receives almost all ofsignal 30 a. Similarly, fiber 604 b receives almost all of opticalsignal 30 b as a result of frustrated total internal reflection ofsignal 30 b at contact surface 50 of fiber 602 b. Signals 30 a and 30 bare indicated using solid lines.

As described above with reference to cross-talk signal 510 in FIGS. 12Aand 12B, reflection of a small, residual portion of signals 30 a and 30b at the interfaces between fibers 604 a and 602 a, and fibers 604 b and602 b, respectively, results in cross-talk signals 610 and 612.Cross-talk signals 610 and 612 are indicated using dashed lines. Aparticular advantage provided by switch 600 illustrated in FIGS. 14A and14B is that switch 600 further processes cross-talk signals 610 and 612so that a large portion of cross-talk signals 610 and 612 are notreceived by output fibers 604 a and 604 b.

Referring to FIG. 14B, return loop fiber 606 a propagates signal 610toward reflective surface 43 of fiber 604 b. Contact surface 50 of fiber602 b frustrates the total internal reflection of signal 610 such thatsignal 610 propagates to return loop fiber 606 b. Similarly, return loopfiber 606 b propagates signal 612 toward contact surface 50 of fiber 604a. Reflective surface 43 of fiber 602 a frustrates the total internalreflection of signal 612 such that signal 612 propagates to return loopfiber 606 a. Only a negligible residual portion of signals 610 and 612,if any, is directed by reflection into fibers 604 a and 604 b. In thisrespect, return loop fibers 606 a and 606 b propagate cross-talk signals610 and 612 until they dissipate. Therefore, switch 600 reduces theeffects of cross-talk signals 610 and 612.

FIG. 15 illustrates a 1×8 embodiment of an optical switch 700 that usesreturn loop waveguides to achieve a cross-talk improvement usingdouble-pass propagation. Optical switch 700 includes optical switches500 a, 500 b, and 500 c arranged in a cascaded architecture. Eachindividual optical switch 500 a-c uses one or more return loopwaveguides 506, as described in detail with regard to FIGS. 11, 12A and12B, to achieve a cross-talk improvement using double-pass propagation.Although optical switch 500 is described as a single channel 1×2 opticalswitch with reference to FIGS. 11, 12A, and 12B, it should be understoodthat switches 500 b and 500 c of switch 700 comprise multi-channel 1×2optical switches.

The operation of switch 700 follows the operation of switch 100described with reference to FIGS. 3 and 4. In particular, if switches500 a, 500 b, and 500 c operate in the appropriate switched orunswitched states described in columns 152, 154, and 156, respectively,of table 150 illustrated in FIG. 4, then the appropriate output channelamong output channels 504 a and 504 b, receives optical signal 30, asdescribed in column 158 of table 150. A technical advantage of thepresent invention is that optical switch 700 reduces the effects of anycross-talk signals generated by undesired reflections in switches 500a-c, as described above with regard to FIG. 11 and FIGS. 12A-12B.

Although the present invention has been described with severalembodiments, a myriad of changes, variations, alterations,transformations, and modifications may be suggested to one skilled inthe art, and it is intended that the present invention encompasses suchchanges, variations, alterations, transformations, and modifications asfall within the spirit and scope of the appended claims.

What is claimed is:
 1. An optical switch, comprising: an input memberoperable to support a first input waveguide, a second input waveguide, afirst output waveguide, and a second output waveguide, wherein the firstinput waveguide has a reflective surface and receives a first opticalsignal and the second input waveguide has a reflective surface andreceives a second optical signal; a reflective output member coupled tothe input member and operable to support a first return loop waveguidethat couples the first input waveguide to the first output waveguide,and a second return loop waveguide that couples the second inputwaveguide to the second output waveguide; and a transmissive outputmember operable to support a third return loop waveguide that couplesthe first input waveguide to the second output waveguide, and a fourthreturn loop waveguide that couples the second input waveguide to thefirst output waveguide, the transmissive output member having a firstposition spaced apart from the input member such that the reflectivesurface of the first input waveguide totally internally reflects thefirst optical signal to the first return loop waveguide forcommunication to the first output waveguide and the reflective surfaceof the second input waveguide totally internally reflects the secondoptical signal to the second return loop waveguide for communication tothe second output waveguide, the transmissive output member having asecond position in proximal contact with the input member such that thethird return loop waveguide frustrates the total internal reflection ofthe first input waveguide and receives the first optical signal forcommunication to the second output waveguide and the fourth return loopwaveguide frustrates the total internal reflection of the second inputwaveguide and receives the second optical signal for communication tothe first output waveguide.
 2. The optical switch of claim 1, whereinthe third return loop waveguide comprises a contact surface operable tocontact proximally the reflective surface of the first input waveguidewhen the transmissive output member is placed in the second position. 3.The optical switch of claim 1, wherein: each input waveguide comprisesan input optical fiber; each return loop waveguide comprises a returnloop optical fiber; and each output waveguide comprises an outputoptical fiber.
 4. The optical switch of claim 1, wherein: each inputwaveguide comprises an input planar waveguide; each return loopwaveguide comprises a return loop planar waveguide; and each outputwaveguide comprises an output planar waveguide.
 5. The optical switch ofclaim 1, wherein: the reflective surface of the first input waveguide isat an angle with respect to the longitudinal axis of the first inputwaveguide; and the third return loop waveguide comprises a contactsurface that is substantially parallel to the angle of the reflectivesurface of the first input waveguide.
 6. The optical switch of claim 1,wherein: the input member comprises a plurality of grooves, each grooveextending from a first face to a second face of the input member; thereflective output member comprises a plurality of grooves, each grooveextending from a first face to a second face of the reflective outputmember; and the transmissive output member comprises a plurality ofgrooves, each groove extending from a first face to a second face of thetransmissive output member.
 7. The optical switch of claim 6, wherein:each input waveguide is positioned along a corresponding groove of theinput member; each output waveguide is positioned along a correspondinggroove of the input member; the first return loop waveguide ispositioned such that a first end of the first return loop waveguide ispositioned along a first groove of the reflective output member and asecond end of the first return loop waveguide is positioned along asecond groove of the reflective output member; and the third return loopwaveguide is positioned such that a first end of the third return loopwaveguide is positioned along a first groove of the transmissive outputmember and a second end of the third return loop waveguide is positionedalong a second groove of the transmissive output member.
 8. The opticalswitch of claim 7, wherein: the grooves of the input member compriseV-grooves formed on a surface of the input member; the grooves of thereflective output member comprise V-grooves formed on a surface of thereflective output member; and the grooves of the transmissive outputmember comprise V-grooves formed on a surface of the transmissive outputmember.
 9. The optical switch of claim 7, wherein: the grooves of theinput member comprise channels formed through the input member; thegrooves of the reflective output member comprise channels formed throughthe reflective output member; and the grooves of the transmissive outputmember comprise channels formed through the transmissive output member.10. The optical switch of claim 1, wherein: the input member comprises acontact face that is at an angle substantially similar to the angle ofthe reflective surface of the first input waveguide; the transmissiveoutput member comprises a contact face that is substantially parallel tothe angle of the contact face of the input member; and the contact faceof the transmissive output member is in proximal contact with thecontact face of the input member when the transmissive output member isplaced in the second position.
 11. The optical switch of claim 3,wherein a portion of the input optical fibers and the output opticalfibers are bundled in a ribbon array.
 12. The optical switch of claim 1,further comprising an actuator coupled to the transmissive output memberand operable to place the transmissive output member in a selected oneof the first position or the second position in response to a controlsignal.
 13. The optical switch of claim 1, further comprising abaseplate, wherein the input member is aligned with the transmissiveoutput member using a plurality of aligning rails.
 14. The opticalswitch of claim 13, wherein each aligning rail comprises: a V-grooveformed on a surface of the baseplate; a corresponding V-groove formed ona corresponding surface of the input member; a corresponding V-grooveformed on a corresponding surface of the transmissive output member; andan optical fiber placed in the channel formed by the correspondingV-grooves of the baseplate, the input member, and the transmissiveoutput member.
 15. The optical switch of claim 13, wherein each aligningrail comprises: a V-groove formed on a surface of the input member; aV-groove formed on a surface of the transmissive output member; and aridge formed on a corresponding surface of the baseplate.
 16. An opticalswitch, comprising: an input member operable to support a first inputwaveguide and a second input waveguide, wherein the first inputwaveguide has a reflective surface and receives a first optical signaland the second input waveguide has a reflective surface and receives asecond optical signal; a reflective output member coupled to the firstinput member and operable to support a first intermediate waveguide thatremovably couples the first input waveguide to a first output waveguideand a second intermediate waveguide that removably couples the secondinput waveguide to a second output waveguide; a transmissive outputmember operable to support a third intermediate waveguide coupled to thesecond output waveguide and a fourth intermediate waveguide coupled tothe first output waveguide, the transmissive output member having afirst position spaced apart from the input member such that thereflective surface of the first input waveguide totally internallyreflects the first optical signal to the first intermediate waveguidefor communication to the first output waveguide and the reflectivesurface of the second input waveguide totally internally reflects thesecond optical signal to the second intermediate waveguide forcommunication to the second output waveguide, the transmissive outputmember having a second position in proximal contact with the inputmember such that the third intermediate waveguide frustrates the totalinternal reflection of the first input waveguide and receives the firstoptical signal for communication to the second output waveguide and thefourth intermediate waveguide frustrates the total internal reflectionof the second input waveguide and receives the second optical signal forcommunication to the first output waveguide.
 17. The optical switch ofclaim 16, wherein: the third intermediate waveguide comprises a contactsurface operable to contact proximally the reflective surface of thefirst input waveguide when the transmissive output member is placed inthe second position; and the fourth intermediate waveguide comprises acontact surface operable to contact proximally the reflective surface ofthe second input waveguide when the transmissive output member is placedin the second position.
 18. The optical switch of claim 16, wherein:each input waveguide comprise an input optical fiber; each intermediatewaveguide comprises an intermediate optical fiber; and each outputwaveguide comprises an output optical fiber.
 19. The optical switch ofclaim 16, wherein: each input waveguide comprise an input planarwaveguide; each intermediate waveguide comprises an intermediate planarwaveguide; and each output waveguide comprises an output planarwaveguide.
 20. The optical switch of claim 16, wherein: the input membercomprises a plurality of grooves, each groove extending from a firstface to a second face of the input member; the reflective output membercomprises a plurality of grooves, each groove extending from a firstface to a second face of the reflective output member; and thetransmissive output member comprises a plurality of grooves, each grooveextending from a first face to a second face of the transmissive outputmember.
 21. The optical switch of claim 20, wherein: each inputwaveguide is positioned along a corresponding groove of the inputmember; the first return loop waveguide is positioned such that one endof the first return loop waveguide is positioned along a correspondinggroove of the reflective output member; and the third return loopwaveguide is positioned such that one end of the third return loopwaveguide is positioned along a corresponding groove of the transmissiveoutput member.
 22. The optical switch of claim 21, wherein: the groovesof the input member comprise V-grooves formed on a surface of the inputmember; the grooves of the reflective output member comprise V-groovesformed on a surface of the reflective output member; and the grooves ofthe transmissive output member comprise V-grooves formed on a surface ofthe transmissive output member.
 23. The optical switch of claim 21,wherein: the grooves of the input member comprise channels formedthrough the input member; the grooves of the reflective output membercomprise channels formed through the reflective output member; and thegrooves of the transmissive output member comprise channels formedthrough the transmissive output member.
 24. The optical switch of claim16, further comprising a baseplate, wherein the input member is alignedwith the transmissive output member using a plurality of aligning rails.25. The optical switch of claim 24, wherein each aligning railcomprises: a V-groove formed on a surface of the baseplate; acorresponding V-groove formed on a corresponding surface of the inputmember; a corresponding V-groove formed on a corresponding surface ofthe transmissive output member; and an optical fiber placed in thechannel formed by the corresponding V-grooves of the baseplate, theinput member, and the transmissive output member.
 26. The optical switchof claim 24, wherein each aligning rail comprises: a V-groove formed ona surface of the input member; a V-groove formed on a surface of thetransmissive output member; and a ridge formed on a correspondingsurface of the baseplate.
 27. The optical switch of claim 16, wherein:the transmissive output member is placed in the first position; thefirst intermediate waveguide is placed in proximal contact with thefirst output waveguide; and the second intermediate waveguide is placedin proximal contact with the second output waveguide.
 28. The opticalswitch of claim 16, wherein: the transmissive output member is placed inthe second position; the first intermediate waveguide is spaced apartfrom the first output waveguide; and the second intermediate waveguideis spaced apart from the second output waveguide.
 29. A method forprocessing a plurality of optical signals, comprising: communicating afirst optical signal in a first input waveguide; communicating a secondoptical signal in a second input waveguide; totally internallyreflecting the first optical signal at a reflective surface of the firstinput waveguide toward a first return loop waveguide for communicationto a first output waveguide; totally internally reflecting the secondoptical signal at a reflective surface of the second input waveguidetoward a second return loop waveguide for communication to a secondoutput waveguide; placing a third return loop waveguide in proximalcontact with the first input waveguide to frustrate the total internalreflection of the first optical signal such that the third return loopwaveguide receives the first optical signal for communication to thesecond output waveguide; and placing a fourth return loop waveguide inproximal contact with the second input waveguide to frustrate the totalinternal reflection of the second optical signal such that the fourthreturn loop waveguide receives the second optical signal forcommunication to the first output waveguide.
 30. The method of claim 29,wherein the third return loop waveguide comprises a contact surfaceoperable to contact proximally the reflective surface of the first inputwaveguide when the third return loop waveguide is placed in proximalcontact with the first input waveguide.
 31. The method of claim 29,wherein: the input waveguides comprise input optical fibers; the returnloop waveguides comprise return loop optical fibers; and the outputwaveguides comprise output optical fibers.
 32. The method of claim 29,wherein: the input waveguides comprise input planar waveguides; thereturn loop waveguides comprise return loop planar waveguides; and theoutput waveguides comprise output planar waveguides.
 33. The method ofclaim 29, further comprising aligning the input member with thetransmissive output member using a baseplate and a plurality of aligningrails.
 34. The method of claim 33, wherein each aligning rail comprises:a V-groove formed on a surface of the baseplate; a correspondingV-groove formed on a corresponding surface of the input member; acorresponding V-groove formed on a corresponding surface of thetransmissive output member; and an optical fiber placed in the channelformed by the corresponding V-grooves of the baseplate, the inputmember, and the transmissive output member.
 35. The method of claim 33,wherein each aligning rail comprises: a V-groove formed on a surface ofthe input member; a V-groove formed on a surface of the transmissiveoutput member; and a ridge formed on a corresponding surface of thebaseplate.
 36. An optical switch, comprising: a first input memberoperable to support a first input waveguide operable to receive a firstoptical signal; a first reflective output member coupled to the firstinput member and operable to support a first output waveguide that iscoupled to the first input waveguide; a second input member operable tosupport a second input waveguide operable to receive a second opticalsignal; and a second reflective output member coupled to the secondinput member and operable to support a second output waveguide that iscoupled to the second input waveguide; wherein the second reflectiveoutput member has a first position spaced apart from the first inputmember such that the first input waveguide totally internally reflectsthe first optical signal to the first output waveguide, and the secondinput waveguide totally internally reflects the second optical signal tothe second optical signal; wherein the second reflective output memberhas a second position in proximal contact with the first input membersuch that the second output waveguide frustrates the total internalreflection of the first optical signal and receives the first opticalsignal, and the first output waveguide frustrates the total internalreflection of the second optical signal and receives the second opticalsignal.
 37. The optical switch of claim 36, wherein: the first inputwaveguide comprises a first input optical fiber; the second inputwaveguide comprises a second input optical fiber; the first outputwaveguide comprises a first output optical fiber; and the second outputwaveguide comprises a second output optical fiber.
 38. The opticalswitch of claim 36, wherein: the first input waveguide comprises a firstinput planar waveguide; the second input waveguide comprises a secondinput planar waveguide; the first output waveguide comprises a firstoutput planar waveguide; and the second output waveguide comprises asecond output planar waveguide.
 39. The optical switch of claim 36,wherein: the first input member comprises a plurality of grooves, eachgroove extending from a first face to a second face of the first inputmember; the first reflective output member comprises a plurality ofgrooves, each groove extending from a first face to a second face of thefirst reflective output member; the second input member comprises aplurality of grooves, each groove extending from a first face to asecond face of the second input member; and the second reflective outputmember comprises a plurality of grooves, each groove extending from afirst face to a second face of the second reflective output member. 40.The optical switch of claim 39, wherein: the first input waveguide ispositioned along a corresponding groove of the first input member; thesecond input waveguide is positioned along a corresponding groove of thesecond input member; the first output waveguide is positioned along acorresponding groove of the first reflective output member; and thesecond output waveguide is positioned along a corresponding groove ofthe second reflective output member.
 41. The optical switch of claim 40,wherein: the grooves of the first input member comprise V-grooves formedon a surface of the first input member; the grooves of the firstreflective output member comprise V-grooves formed on a surface of thefirst reflective output member; the grooves of the second input membercomprise V-grooves formed on a surface of the second input member; andthe grooves of the second reflective output member comprise V-groovesformed on a surface of the second reflective output member.
 42. Theoptical switch of claim 40, wherein: the grooves of the first inputmember comprise channels formed through the first input member; thegrooves of the first reflective output member comprise channels formedthrough the first reflective output member; the grooves of the secondinput member comprise channels formed through the second input member;and the grooves of the second reflective output member comprise channelsformed through the second reflective output member.
 43. The opticalswitch of claim 36, wherein: the first input member comprises a contactface that is at an angle substantially similar to the angle of areflective surface of the first input waveguide; the second reflectiveoutput member comprises a contact face that is substantially parallel tothe angle of the contact face of the first input member; and the contactface of the second reflective output member is in proximal contact withthe contact face of the first input member when the second reflectiveoutput member is placed in the second position.
 44. The optical switchof claim 36, further comprising an actuator coupled to the secondreflective output member and operable to place the second reflectiveoutput member in a selected one of the first position or the secondposition in response to a control signal.